This invention relates to compositions and processes for preventing the build-up of plant, animal and microbial encrustations on surfaces and for preserving wood utilizing organotin compounds of the type hereinafter disclosed. Surfaces treated in the manner of this invention remain free from biological encrustations and wood so treated remains well preserved after exposure to a variety of decay causing environments. Surfaces so treated have high paintability.
The necessity for applying various preservatives to wood to prevent decay or "rot" is clearly accepted and several million pounds of wood preservatives are used industrially each year. Untreated wood is subject to a variety of decay and rot causing influences including damage by bacterial and fungal infestation and damage by insects, especially termites. Furthermore, in water certain marine animals bore into wood and cause serious damage. Various rodents gnaw on wood and thereby cause rapid deterioration. For these reasons, wood preservatives should be capable of destroying or repelling a wide variety of organisms and microorganisms, including bacteria, fungi, insects, mollusks and rodents.
A variety of chemicals are commonly used as wood preservatives, including such well-known substances as creosote and pentachlorophenol. Combinations of toxic materials such as FCAP (Fluoride-Chromate-ArsenateDinitrophenol) are also used for this purpose. However, many of the heretofore used wood preservatives suffer from various shortcomings. For example, wood treated with creosote has essentially no paintability. Wood treated with some of the more toxic wood preservatives is not suitable in barnyard lots where cattle can gnaw the wood. Some wood preservatives are sensitizers and cannot be used for treating bleachers and seats. For these and other reasons, there is a continuing need for new and improved wood preservatives agents.
At the same time, surfaces other than wood require protective coatings, especially when said surfaces are in contact with a marine environment such that buildup of various biological encrustations becomes a problem. For example, it is well known that barnacles, encrusting bryozoans, various algal forms, bugula, hydroids, oysters, tunicates, tube worms and ill-defined slime films comprising a mixed microorganism population attach themselves to concrete, wood and metal pier pilings, ship bottoms and the like. Removal of such films requires expensive mechanical scraping or sandblasting. Although a variety of chemical paint additives and coatings suitable for preventing the buildup of such encrustations are known in the art, these materials all suffer from a variety of disadvantages. For example, cuprous oxide, a common anti-fouling paint additive, must be used at extremely high levels, up to about 50% by weight of the anti-fouling composition, thereby limiting the types of formulations that can be prepared. The mercury anti-fouling compositions well known in the art are more toxic than copper oxide and pose potential ecological problems. Furthermore, many such mercury derivatives are corrosive to light metal alloys such as aluminum and must be avoided when aluminum ship bottoms are being treated. Organotin compounds, especially bis(tri-n-butyltin) oxide, have been used as anti-fouling additives for coating compositions. However, coating compositions containing the organotin oxides need to be re-applied periodically after immersion in a marine environment. For this reason, a continuing search has been made to provide suitable organotin compounds having improved and prolonged anti-fouling activity.
Accordingly, it is an object of this invention to provide a method for preserving wood (including fibreboard and compacted cellulosic wood substitutes) by applying one or more of certain (organothiomethyl)triorganotin, (organosulfonylmethyl)triorganotin and (N,N-disubstituted aminomethyl)triorganotin compounds thereto. Another object herein is to provide improved anti-fouling compositions especially suitable for use on metal, wood, concrete and the like, surfaces exposed to a marine environment. These and other objects are obtained herein as will be seen from the following disclosure.
The organotin compounds used in the present process as well as methods for their preparation are fully described in the copending applications of Peterson, entitled "Novel Organotin Herbicidal Compounds," Ser. No. 23,457, filed Mar. 27, 1970; "Novel Organotin Compounds," Ser. No. 10,303, filed Feb. 10, 1970; "Compositions and a Method for Controlling Weeds with Organotin Compounds," Ser. No. 23,019, filed Mar. 26, 1970, incorporated herein by reference.